Note, if you are making The $50 Robot (or at least using the ATmega8 microcontroller), download this .hex file and upload it to your ATmega8. You dont need to compile anything, as I already did that for you. This program will tell the microcontroller to send a signal at 1.5ms, the signal your servos need to hold at the zero position.

Before you make it a photovore, you have to modify your servos. To modify your servos, you need a program that tells the servos to center. That is the first program you should download. After you have downloaded it and modified your servos, download the photovore code. Downloading the photovore code into the microcontroller will erase the unneeded center servo code.